Diamond drill feed control



H. s. HbFFAR DIAMOND DRILL FEED CONTROL Oct. 21, 1941.

Filed July 12', 19:59

2 Sheets-Sheet 1 Patented Oct. 21, 1941 DIAMOND DRILL rnnnqqnrnop HenryS. Hoffar,

C n da, assienor .t Drills, Ltd, Vancouver Vancouver, British Columbia,

International Multilfieed r.iti, h Columbia Qanada a corporation ofBritish Cdl iimlfia Application July 12, 1939, Serial No. 284 ,0 67 6Claims. (01. 255-4 My invention relates to devices for drilling rock.The invention is best illustrated in conjnnction with a diamonddrilL-butcertain principles thereof, as will appear hereafter, may be appliedalso to percussion rock drills. The invention is concerned primarilywith the feed arrangements for such drills, having in mind theconditions under which they are intended to operate. 7

It is considered preferable, in the operation of certain diamond drills,to employ high speed rotation, and rather light pressure to advance thedrill red, sincetherebythe life of the diamond points can be materiallyincreased. However, it is desirable to advance the drill as rapidlyasitis capable, without undue wear, of cutting through the rock, but therate'o-f feed is-a variablequantity; and depends upon the resistanceencountered, which in turn depends upon the-rock formation with whichthe point isengaged, and, as such factors vary from time to time, arateof advance which'would' be 'permissibleundersome conditions might beunduly rapid and destructive of the drill point if persisted in underother conditions. It has not been considered practicable to provide anautomatic feed, either-hydraulic, pneumatic or mechanical, which wouldbe wholly self-adjusting to the 'dif ferent conditions encountered fromtime to time, to accomplishadvance of the drill at whatever ratebest'suited to the conditions momentarily jenconntered, and changingfrom' moment to moment, yet Ihave discovered'how this'may be done, andit is an object of the present invention to provide feed arrangementsand controls to accomplish the above end. *It is also desirable toprovide means, when employing a pressure fluid as the primary means{to-accomplish advancejto accomplish manual feed when desirable, and toprovide further means whereby, should the drill point pass into 'afissure or r'ock'chamber, it will not advance suddenly under theappliedpressure across the fissure and strike the opposite wall, for suchimpact is'extremely destructive of the' diamond peints. Such occurrencesare infrequent, yet it is' desirable to provide means, if that can bedone without-undue complications, whereby, in a drill employing apressure fluid as the primary advancing means, restraint can be imposedupon the advance to prevent such unrestrained plunging; forward when theresistance is wholly removed. v @It 'is also desirable to provide feedmeans or feed controlling means, especially for use where 55 ftion"npona mine bar,

the advance is primarily accomplished under the influence 0f a.pressiire fluid, whereby the permitted maximum rate of*advance Inay'bevariedjat willto' suit diiierent" operating conditions," yet"'withoutincreasing the pressure at the drill point, and it is' an object" ofthepresent invention to provide control means adjustable as @1 9 Diamonddrills, particularly such as are portare: th is a' b iq :beine f b rte fm pint to point andfsuppoifted'in operative posi-r a ,r i have-m w n ide a pressure-cylinder and a piston movablejtherewe a amni na a e of "than a the ri red *b' fi iEihfi iw t dih pennation of the-piston orextending through fitf, in 1 1 mann t a i F r Q th r ll' edi enthe0 teiof ww e stati ns it as one saw" t h v vai ab e" a 9 w tra e are; manlytwice the -al len th fa ithe il o v t ieeaj l n i i Whe 'ope atinislicrampe Quarte s. a in a m e drift or tunnel, working space is limited;and it a nece sary und uch. cond tions to sho t n the length githedrillitself to about half the available. s hereby necessitatin frequentsto age p ck feed citric piston, and 'for to 'nj"t1on. 0f additionallengths to the can ,m i. hidtdid consume timabut it r e-I- we?" a i sapn re deeam it ate r yid fi i" me hanism or such g ve a ee h o advanceeual es aetn ivtheentir c ear s ace available, tqt e end, i stoppa es maythe le frequent 39 secti n mbee pneat and it an object ,Qft enr se r l.tenti nxto provide feed machae orl iesjhavingi the. capabilities andadvan a es indicated, and which is also'suited to the; othernecessary-conditions which it -encountersin use, V

Q .It isaiurtherohject to. provide feed mechanism pf :the .sortindicated, incorporating a cylinder tand alslide esters-any thereof,connected to the piston within by a casement over sheaves cat oppositeends of" the cylinder, which slide supports; a rota-tive motor in thecase of a diamond drill, or a rtativeor reciprocativeper- .eussiondevice' in the case of a rock drilh' which device; in either'instance,is so mounted that it may beswung aside out off the {line of the drillrod, so that, for instance in a" diamond drill, additionalsectionsmayfbe coupled on, or the e r ama emlia t i stilla-iurtherobject is the improvement in order to accomplish feed Figure lis a perspective view, with parts carried by the mine bar, the head [1being permanently secured to the exterior of the cylinder, as bywelding. By reason of the projection of the head I! the slide 3 may notbe completely circular, but is saddle shaped, as is best seen in Figure4. To prevent its rotation around the cylinder a key 31, received in agroove in the exterior of the cylinder, is received likewise in acorresponding groove in the slide 3.

Carried by the slide 3, but preferably indirectly through interposedmeans, which will be described, is a coupling broken away, illustratinga diamond drill, the

feed mechanism of which isIinop'erative position with relation to themine b'ar and to'the drill rod, but in which the rotative motor andcoupling to the drill rod have been swung aside for access to the drillrod.

Figure 2 is a longitudinal feed mechanism, of Figure 3, the parts beingrearranged somewhat from the showingin Figure 1 for com venienceofillustration. v b I 1 Figure 3 is a part elevation and; part section,taken onthe line 3- 3 of Figure 2, and Figure 4 a transverse sectionsubstantially'on the line 4 4 of Figure 3. H I A pressure fluid is stillemployed as the primary forcing or advancingmeans and hence within acylinder I, closedby theendslll and H, islslidable a packed piston 2.The cylinder heads!!! and II are hel'dupon the ends of the cylinder l toclose it, preferably bytension means extending through the cylinder andthe piston, as shown at [2 and I3. In effect these are tension-rods, andthe member I2 isan actualrod anchored at the two ends. The member I3 isa hollow'rod, howeverphaving an aperture l4 atone end', withinthe'cylinder, the rod extending through the head II at this vend andprovided 'with a cap l5ft'o closethis end, so that fluid entering fat'the' opposite end, adjacent the head ID, will be. admitted'into thecylinder through the aperture l4. w The cylinder is made ofapproximately the len'gtho'f the clear space; and while certain devices,applied externally, reduce the length of the cylinder somewhatyit isof'a length considerably more than" half the expected "feed distance; and

section through such I substantially on the "line 2-2- affords anextent-ofadvance considerably more than half the clear distance. To thisendyinstead of a rigidpiston rod projecting from the piston 2-, aflexible cable- 22 is-anchored at 20 in the piston, extendsthroughsuitable packing glands 2 I atthe cylinder heads, and thence oversheaves 23 supported externally uponeach cylinder headn Being.thusr'eversed-in direction, externally ofthe cylinder, the cable22-extends to a slide 3 mounted upon andguided for movement lengthwiseof. the cylinder l, to which slide the cable 22 is anchored, asindicated-at 24. A suitable guard 25 may surround the.sheaves 23. Bysuchan expedientthe piston 2.may move substantially the full length of.thecylinder i, being stopped in this instance by the glands 2| or bysuitablestops at about this point, or by stops engaging the slide .3, which is connected .to the drill rod D. The slide 3 may have a length oftravelequalto the travel of the piston within the cylinder, and yet thecylinder may .be made of a length almost equal ,to the full extent ofclear space in the drift.

The cylinder l is normally mounted for swiveling upon a mine barlvlbymeans ofa swive head Hreceived in a similarly shaped socket 5 which isadapted to fit within the end of the drill D. Since the coupling 5. ismounted upon the slide 3 it partakes of the latterslengthwise movement.The coupling 5, especially in the case of a diamond drill, is likewiserotative about the axis of the drill rod, rotation being accomplished insuch a case by a rotative motor 4. The form of this motor is largelyimmaterial. As shown herein it is a rotary motor intended for operationby compressed air and its form and arrangementis of importance to theremainder of the invention only in that it is somewhatunbalanceddynamically, and thereby tends to produce vibration. Being directlycoupled to the drill rod, it is intended for rotation at the rate ofrotation best suited for operation of the drill.

This motor 4, being in alignment with the drill during normal drilling,is preferably so mounted that it may be swung aside when it is desiredto engage the drill rod to withdraw it, or when it is de'siredtocoupleon a further length of drill rod. Accordingly the motor 4 ismounted pivotally or swingably upon theslide 3 at 43, and is normallyheld to the slide, against swinging, by a swingably mounted bolt 42receivable within a fork34 of the slide 3. In Figure 4 the motor isshown in operative position, and in Figureil it is'shown swung'aside.Hose connections for supply of pressure fluid or for water supply havebeen omitted from the drawings, but would be flexible to permit suchswinging. InFigurel there is-shown the control valve 4| for regulatingthe supply of the pressure fluid for rotating the motor 4. The motorsshaft 40 is in alignment with the drill rod D and one end of its shaftcarries the coupling 5 when in the position of partsshown in Figurel.

' It is convenient to note at this point thata pressure fluid, whetherair or water or oil, is supplied to the interiorof the cylinder I, atone side or theiother of the piston 2, through the head Ill. The fluidis supplied by a connection at L60 'past' a metering valve 6!, and pasta four-way valve 6, controlled by the handle 62,-by means of which thepressurefluid may enter directly through the head H], by way of theconnection at 63, or by way of a connection filto the end of the hollowrod l3, -previously mentioned, and by means of which the -pressurefluidis admittedito'the" distant face of the piston. A pressure limiting orreducing valvemayalso be eniployed at this point, if desired orrequired. a The feed mechanism thus far described is op erativewithoutmore to efiect feed, under the influence of thepressure-fluid actingupon the piston 2, and to eifect drilling under theinfluence ofrotationeifected by rotation of the motor 4. However, there are timeswhen it is desired to enploy hand feed, or to control manuallyv therate; or extent of feed, and Ihave therefore prolvided a manual feedscrew, and in so'doing I have discovered that such a feed screw, whenemployed in-conjunctionwith the pressure fluid .cnt,"s'er've also tocontrol the rate of advance automatically without. the interposition ofany 'nianual means or control, precisely in accordance with the extentof resistance encountered. The feed screw 1 is journaled by combinedrotativeand thrust bearings in the opposite heads, of the cylinder. Thesaddle or slide 3 is provided with a trough through'which the feed screw7 passes; but with which it has no threaded engagement. This troughmerely serves to position it, and to backit up when the feed screw isengaged by a half nut II. This half nut H is guided in a frame 31 uponthe slide 3, and its position is controlled by a screw 12 connectedthrough a swivel with the nut II, and provided with a handle 13 wherebythe screw 12 may be rotated. By backing 01f the nut H the feed screw 1may be left wholly free of the slide 3, and consequently of the piston2, and under such conditionsthe feed is" accomplished wholly by means ofand under control of the pressure fluid. If the opposite ends of thecylinder are vented to remove artificial resistance of the fluid toadvance, feed may be accomplished wholly under manual control throughthe feed screw 1, and by means of an operating or turning arm 15secufable upon an end of the screw 7.

However, when operating under the influence of the pressure fluid, Ihave discovered that if the nut H be left in engagement with the screw1, control of the advance may be accomplished with little effort, andmanually, by turning the handle 15, and indeed may be accomplished vwholly automatically, the handle turning to permit advance, but only ata rate which is a function of the length of the arm and the mass of thehandle 15, which constitutes an unbalanced weight afiecting theperiodicity or amplitude of the vibrations generated by the motor 4, thevibration also being affected somewhat by the resistance of the rockencountered by the drill point.

It is not entirely clear to me just why this action occurs. It has beendiscovered by me in practice, and I have discovered how the same may becontrolled and regulated, but the operation is substantially the same nomatter in what direction the drill point is operating, whether down, up,or laterally. The action is always to feed the drill point forwardly byautomatic rotation of the feed screw 1 in the proper direction, but onlyat a rate which is consistent with the resistance encountered by thedrill point. If the resistance increases, the speed of rotation of thedrill point and of the motor 4 is reduced, thereby reducing the rate orperiodicity of vibration of the entire assembly, and in consequencedecreasing the rate of rotation of the feed screw 7, and thereby therate of advance. The rate of advance is thus automatically compensatedand made to correspond to the resistance encountered, and a diamonddrill, thus equipped, in operation, operates by repeated surges as thedrill speeds up and then meets increasing resistance and slows down, andthen speeds up again. The variation in speed is not appreciable, butsufficient to be noticed.

In attempting to explain this action it appears to me that the pressureof the pressure fluid against the piston reacts through the cable 22,the slide 3, and the nut 1| upon the screw 1, tending to create frictionto hold the screw against rotation, though, by pressure, tending toslide the nut along the incline of the screw thread, and thus to inducerotation of the screw. However, the whole assembly; is set into vibration' by the rotation of the motorl as it isaffected by the dynamicallyunbalanced handle '15. This effects momentary release of the nut fromthe feed screw, because there is necessarily working clearance betweenthe two, and since the fluid pressure on piston 2 presses the nut alongthe screw, it'tends to rotate, its thread sliding down the thread of thenut H. Rotation in the proper direction is assured because the follow-upof the piston pressure prevents reverse rotation, and tends to" slidethe nut down the screw thread, inducing the screws'rotation in theproper direction. The extent to which it may feed is thus dependent uponthe. periodicity and amplitude of the vibration, since change in itsperiodicity affects the number of releases and reengagements between thenut and screw, and the amplitude affects the severity of the shockbetween them, upon each engagement. I have found that variation of thelength of the arm of handle 75 upon the screw influences the rate ofadvance by itsaifect on the vibration, with a given screw pitch.Consequently in order that the rate of advance may be controllable, thehandle 75 is'slidably received in the head 16 secured upon thesquaredend ll of the feed screw 'I.- The handle is held in arl'yadjustedposition, transversely of the axis of the screw, by such means as thes'et screw i8. By adjusting the handle 15 outwardly the rateof feed isincreased, and vice versa.

Whatever may be the true explanation, the device has been found tooperate thus in practice, and there is provided by such means anextremely desirable and eificient regulation of the rate of advance byadjustment of the length of the handle arm, and automatically within therange corresponding to the handle setting in accordance with momentarychanges in resistance encountered by the drill rod, to the end that thedrill may continue to rotate at maximum speed and rate of advance, andyet be automatically protected from too great advancing pressure, orfrom too high speed consonant with the pressure actually applied.

What I claim as my invention is:

1. A diamond drill or the like comprising a coupling for connection tothe drill rod, a slide carrying said coupling, a closed cylinderdisposed parallel to the drill rod and constituting a parallel guide forsaid slide, a piston slidable lengthwise within the cylinder, means tosupply a pressure fluid within the cylinder to accomplish such movementof the piston, a sheave at each end of the cylinder, a cable, suitablypacked at the cylinder heads, anchored to the piston and to the slide,and extending over the sheaves, to transmit lengthwise movement of thepiston to the slide, coupling, and drill rod, a screw and nut extendingparallel to the cylinder, and operatively connecting the cylinder andthe slide, and means efiecting vibration of the assembly during fluidfeed, thereby to regulate the feed rate automatically through the screwand nut.

2. A diamond drill or the like comprising a slide and a coupling carriedthereby for connection to the drill rod, a cylinder and a pistonslidable lengthwise thereof, and operatively connected to the slide toadvance the coupling and the drill rod, means to supply a pressure fluidwithin the cylinder to eiTect such advance, a screw journaled upon andextending parallel to the cylinder, a nut engaged with the screw andcarried by the slide, an arm projecting radially from the screw, andmeans efiecting vibration of the assembly during fluid feed, thereby toregulate the feed rate along the screw, in accordance with the characterof the vibration governed by the effective length of said arm.

3. A diamond drill or the like comprising a coupling for connection tothe drill rod, a closed cylinder and a piston slidable lengthwisethereof, a slide carried by and guided upon the cylinder for lengthwisemovement, a rotative motor carried by the slide and operativelyconnected to the coupling, an operative connection between and theslide, including a cable aneach and guided at the ends of the pressurefluid within the piston chored ,to cylinder, means to supply a thecylinder to effect advance of the piston, and reverse feed of the slideand coupling, a feed screw parallel to and journaled upon the cylinder,an arm projecting laterally therefrom, and a nut carried by the slide,and engageable with the screw, vibration of the assembly upon rotationof the motor, permitting advance of the slide and coupling at a ratedependent upon the resistance encountered and the degree of lateralprojection of said arm from the screw.

4. The combination of claim 3, including means operable at will toretract the nut from engagement with the screw.

5. A diamond drill comprising a cylinder and a piston movable lengthwisetherein, heads closed upon the cylinder sure fluid feed means of thecylinder, a slide guidfor movement lengthwise thereof, means, includinga cable anchoredto each of the piston and. slide, and runningover guidesat eachend of the cylinder, for moving the ,slide equally and oppositelyby movement of the piston, a couplingior connection to the drill rod,carried by said slide, means extending through the piston and cylinder,and holding the ing the opposite ends heads upon the cylinder, saidlatter means including a hollow, rod connected at one end. to a.pressure fluid source, and opening within the cylinder beyond thepiston, for supply of pressure fluid for advance of the piston andslide, and valve means to control the supply of pressure fluid throughsaid hollow rod. 7 6. In a rock drill, the combination of a support, adrilling and drill-engaging means, a presto advance the drill-engagingmeans, a feed screw and nut operatively connected between the supportand the drill-engaging means, and subject to pressure of the fluid feedmeans, vibratory means, a mass carried by the screw eccentricallythereof, and means to adjust the degree of eccentricity of the mass,thereby to regulate the vibration of said vibratory means which in turninfluences the rate of relative rotation of said feed screw and nut, andconsequently regulating the rate of advance of said drill-engaging meansgoverned by such relative feed screw and nut rotation.

HENRY s. HOFFAR.

